The initiative will support theoretical physics research across twelve institutions based on a series of recent developments in theoretical physics which have revealed that even large macroscopic systems consisting of many atoms or electrons — matter — can behave in an essentially quantum way. Such ultra-quantum matter (UQM) allows for quantum phenomena beyond what can be realized at the level of the individual atom or electron, including distributed storage of quantum information, fractional quantum numbers, and perfect conductivity. The Simons Collaboration on Ultra-Quantum Matter will work to classify possible forms of UQM, understand their physical properties, and provide ideas designed to enable new realizations of quantum materials in the lab...